The present invention is directed to a method of and apparatus for the deaeration of liquid in a closed circulation system, particularly for a heating system with a water boiler.
Water has the natural property of absorbing air from gas in the water and the presence of air in the water is particularly disadvantageous in a heating system. In heating systems in high rise buildings with the boiler located in the basement, frequently there are large accumulations of air in the heating members located on the higher floors and, as a consequence, the heating members or radiators remain cold. The problem is that the flow of water through the heating members is interrupted by the air.
Due to the high pressure present in the boiler, the relatively low level heating of the water is insufficient to release dissolved gases which could be separated out in a microbubble deaerator as disclosed in German Offenlegungsshrift No. 2 200 904. As a result, the water is in an unsaturated condition during the cooling process which permits air to separate out of the water in the heating member located at the higher elevations of the system. As the water flows upwardly, microbubbles gradually form in the water with a progressive reduction in pressure and the bubbles have sufficient time and capability to rise, since they flow slowly through the heating members. Accordingly, the microbubbles end up as air accumulations in the heating members which block the flow of water. Therefore, it is known in practice to repeatedly remove in a manual operation the air present in the system through vent valves, however, such a removal operation is both time consuming and costly.